Mission success of spacecraft, aircraft, and rockets is dependent upon components and instrumentation (collectively referred to as “components” herein) continuing to operate throughout an entire flight and beyond deployment, for example, in the case of a satellite. But such components are often sensitive to launch and spacecraft dynamic environments. These dynamic environments can include vibrations having a wide range of frequencies and shocks, varying temperatures, and exposure to unintended electrical currents. The more severe the dynamic environment, the more costly it can be to protect the components.
Previous attempts have been made to manufacture isolators that isolate components from shock and vibrations. Such isolators may be found in, for example, spacecraft, aircraft, the automotive industry, and industrial manufacturing. These previous isolators include: springs and elastomer isolators integrated in a chassis structure through nut and bolt connections, wire rope isolators that traditionally have a higher load capacity than elastomers, constrained layer dampeners, and tuned mass dampeners. Alternatively, the operation of an instrument or component may be regularly adjusted and corrected to account for the effects of a dynamic environment by using a co-located accelerometer or other sensor that provides feedback for purposes of making such corrections. Existing isolators include both passive and active isolators. However, these prior art isolators are inadequate at isolating the component from a range of vibration frequencies—including high and low frequencies—and typically do not isolate the component from thermal loads and electrical currents. Some solutions include relocating the components to a different area of the vehicle or structure where the dynamic environment may be different and/or providing the components and/or isolators with a more robust design. One such solution is to add a dumb mass to an existing isolator and associated component subsystem. The dumb mass shifts or alters the characteristics of the system to respond differently and avoid targeted vibrations. Any weight, including dumb mass weight, is costly in some industries, such as the aerospace industry where weight is limited. Therefore, adding extra weight like the dumb mass can be a significant disadvantage. Other solutions use analysis corrections to compensate for the unwanted environmental frequencies detected by the instrumentation.
Wire rope isolators use friction in the wire rope to help absorb vibration and energy. In some situations, wire rope isolators often use a series of wire rope loops where each loop is the same size and shape. Such devices only dampen one mode or a relatively narrow frequency range. Other wire rope isolators may include two or three differently sized wire rope loops, and these isolators will only dampen two or three specific modes or two or three narrow frequency ranges. Another disadvantage is that wire rope will twist when configured into the final isolator design, requiring adding an axial pin to prevent twisting and to compel axial movement, i.e., to keep the isolated component moving up and down in the axial direction. Wire rope isolators also include parts to secure the rope, axial pin, and any platform interconnected to the isolated component. Every extra part in an isolator is another part that can break, that adds extra weight, and that must be manufactured and assembled. Further, every additional part is another piece that can vibrate, rattle, or come loose and damage other components. Therefore, any extra part is a disadvantage of the isolator design. Wire rope isolators are also difficult, expensive, and time-consuming to modify or customize.
Prior art isolators also tend to be symmetrical in design. The symmetry is often driven by manufacturability considerations. However, symmetry can be a disadvantage. Symmetry in an isolator tends to enable greater effective modal mass which provides a mechanism to drive loads into an isolated component, whereas an asymmetrical design according to aspects of the present disclosure distributes effective modal mass and reduces loads experienced by an isolated component. Asymmetry can be introduced into wire rope designs by the fact that the ends of the rope may need to be tied, overlapped, or secured in a way that creates asymmetry, or where the wire strands used to construct the wire rope are non-uniform. But such modest asymmetry has little overall positive effect, is often an unintentional artifact of the manufacturing process, and is not a deliberate design choice.
Accordingly, there exists a significant and long-felt need for an isolation device that isolates vibrations, shocks, static loading, thermal loads, and electrical currents and that distributes the effective modal mass across a broad range of frequencies.